Basalt fiber and polycarboxylate superplasticizer effects on freeze-thaw durability of cement-fly ash stabilized aeolian sand gravel

The durability of cement-fly ash stabilized aeolian sand gravel base (CFSAGB) materials was enhanced using basalt fiber (B) and polycarboxylate superplasticizer (P). Four BP-CFSAGB mixtures with varying B-P dosages were prepared. Mechanical properties were evaluated after freeze-thaw cycling in multiple salt environments. Strength was significantly improved. The optimal mix showed 32.2% higher compressive strength and 42.9% higher tensile strength than the control after 10 freeze-thaw cycles in a 0.5% NaCl-5% Na₂SO₄ solution. Deterioration was found to be a physicochemical process dominated by physical damage. Basalt fibers alleviated internal stresses through crack bridging. The superplasticizer improved particle dispersion and stabilized hydration products. Although acting independently, their effects proved complementary. Microstructural analysis via scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) confirmed the formation of denser matrices and more stable hydration phases in the modified mixtures. These findings demonstrate that the combined use of B and P can significantly improve the freeze-thaw resistance of cement-stabilized granular base layers. The results provide mechanistic insight and technical support for the design of durable pavement base courses in salt-affected regions.